Antenatal administration of glucocorticoid (CS) reduces incidence and severity of respiratory distress syndrome (RDS) in premature infants. Previous trials done before the advent of surfactant therapy indicated that antenatal treatment with thyrotropin-releasing hormone (TRH) plus CS significantly reduces the occurrence of chronic lung disease, compared with treatment with CS alone. The randomized controlled trial tests the efficacy of antenuated TRH when postnatal surfactant therapy is used and investigates the mechanisms by which combined treatment with TRH and CS is effective. Status: Three enrolled in 1997. Enrollment and data analysis of short term outcome completed, subject follow-up phase data collection underway.